Zinc protoporphyrin
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| Names | |
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| Other names
Zinc protoporphyrin IX
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| Identifiers | |
| ChEBI | |
| ECHA InfoCard | 100.035.853 |
| KEGG | |
| MeSH | zinc+protoporphyrin |
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PubChem CID
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| Properties | |
| C34H32N4O4Zn | |
| Molar mass | 626.032 g/mol |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |
Zinc protoporphyrin (ZPP) is a compound found in red blood cells when heme production is inhibited by lead and/or by lack of iron. Instead of incorporating a ferrous ion, to form heme, protoporphyrin IX, the immediate precursor of heme, incorporates a zinc ion, forming ZPP. The reaction to insert a ferrous ion into protoporphyrin IX is catalyzed by the enzyme ferrochelatase.
Measurement of zinc protoporphyrin in red cells has been used as a screening test for lead poisoning. and for iron deficiency. There are a number of specific clinical situations in which this measurement has been found to be useful.
Zinc protoporphyrin levels can be elevated as the result of a number of conditions, for instance:
The virtue of elevated ZPP testing as a screen is that all of these conditions can be considered worth discovering.
The fluorescent properties of ZPP in intact red cells allows the ZPP/heme molar ratio to be measured quickly, at low cost, and in a small sample volume.
More recently, ZnPP is finding a new use as a drug in combined cancer therapies.
Porphyrin compounds containing zinc have been known since the 1930s. They became of more than academic interest with the discovery, in 1974, that ZPP was the major non-heme porphyrin formed in red cells as the result of lead poisoning or iron deficiency.
It was already known at this time that non-heme Protoporphyrin IX levels were elevated in these conditions, but prior investigators had used acidic extraction methods in their assays that converted ZPP to unbound Protoporphyrin IX.
The early literature is sometimes confusing, and results are hard to compare without detailed examination of the measurement methods and the conversion factors used to report the results. Reports may refer to free erythrocyte protoporphyrin (FEP) or erythrocyte protoporphyrin (EP or EPP). ZPP is also abbreviated ZP and ZnPP. Current practice is tending to measure and report the molar ratio of ZPP to heme (μmole/mole).
ZnPP is finding a new use in cancer therapies. Research into the field of nanotechnology is finding a use for many compounds which show different and often more favorable properties at the nanoscale. ZnPP is one such compound that can effectively aid in the treatment of multiple types of cancer in laboratory experiments. The clinical application of the nanomaterial ZnPP will only come through continued research and more definitive results.
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